Rain unauthorized debit

I used rain sim for internet until I moved to a new area, I realised rain wasn't working here and called them to find out if they had coverage and they comfirmed rain was not efficient in the area.

To my understanding, rain internet deal was month to month, I'm surprised that rain now debited an amount of 1.6k in total but I've not been using the sim in over 2 months.

How can this be???